Fully integrated analog PI controller

Abstract

A fully integrated analog PI controller solves the problem that the capacitance of an analog PI controller of the order of nF and uF cannot be integrated, and belongs to the technical field of electronic circuits. The analog PI controller of the present invention converts voltage into current through a negative feedback circuit; the output voltage of the PI controller is obtained by injecting current into an RC branch composed of an equivalent capacitor and a resistor; and the value of the on-chip capacitance is amplified by using an impedance converter to obtain an equivalent capacitance, thereby achieving full integration of the PI controller.

Description

Technical Field

[0001] The invention relates to a fully integrated analog PI controller, belonging to the technical field of electronic circuits. Background Art

[0002] PI controller is a classic closed-loop controller, which is widely used in various industrial closed-loop control systems. It can realize precise control of various parameters and improve the stability and performance of the system. PI controller can be divided into two types: digital PI and analog PI. Digital PI controller is a PI controller based on digital signal processor or microcontroller. It realizes the control of the system by digitally calculating the sampled data of the system. Digital PI controller has higher accuracy, flexibility and stability, and is suitable for complex control systems.

[0003] The advantages of analog PI controllers over digital PI controllers are as follows: 1. No sampling and conversion of digital signals is required, and real-time control response can be achieved; 2. The circuit structure is relatively simple, and there are no noise and interference problems that may occur in digital control systems; 3. Low cost, because digital PI controllers require hardware support such as digital signal processors or microcontrollers, while analog PI controllers can be implemented through simple analog circuits; 4. The adjustment parameters of analog PI controllers are usually more intuitive, easier to understand and debug, and are suitable for some scenarios with simpler control systems.

[0004] Analog PI controllers are usually composed of operational amplifiers, resistors, and capacitors. In order to meet the requirements of integration and filtering, the capacitors are usually set to nF or even uF. Capacitors of this magnitude cannot be integrated, which affects the integration of the overall closed-loop circuit, resulting in space occupancy and increased costs. Summary of the invention

[0005] Aiming at the problem that the capacitors of the analog PI controllers of nF and uF levels cannot be integrated, the present invention provides a fully integrated analog PI controller.

[0006] A fully integrated analog PI controller of the present invention comprises an operational amplifier A1, a MOS tube M1, a MOS tube M2, a MOS tube M3, a resistor R1, a resistor R2, a current source I1, an equivalent capacitor Ceq1 and an equivalent capacitor Ceq2;

[0007] The positive input terminal of the operational amplifier A1 is the input terminal Vin of the analog PI controller, the negative input terminal of the operational amplifier A1 is connected to one end of the resistor R1 and the source terminal of the MOS tube M1 at the same time, and the output terminal of the operational amplifier A1 is connected to the gate terminal of the MOS tube M1;

[0008] The drain end of the MOS tube M1 is simultaneously connected to the drain end of the MOS tube M2, the gate end of the MOS tube M2 and the gate end of the MOS tube M1;

[0009] The drain end of the MOS tube M3 is simultaneously connected to one end of the resistor R2, one end of the equivalent capacitor Ceq1 and the positive electrode of the current source I1, and is the output end Vout of the analog PI controller;

[0010] The other end of the resistor R2 is connected to the other end of the equivalent capacitor Ceq2, and the other end of the resistor R1, the other end of the equivalent capacitor Ceq1, the other end of the equivalent capacitor Ceq2 and the negative electrode of the current source I1 are connected to the GND of the power supply;

[0011] The source ends of the MOS tube M2 and the MOS tube M3 are connected to the power source VDD.

[0012] Preferably, the equivalent capacitor Ceq1 includes an operational amplifier A2, an operational amplifier A3, an operational amplifier A4, resistors R3-R8 and a capacitor C1;

[0013] One end of the resistor R3 is one end of the equivalent capacitor Ceq1, one end of the resistor R3 is connected to the positive input end of the operational amplifier A2, the other end of the resistor R3 is simultaneously connected to one end of the resistor R4 and the output end of the operational amplifier A4, the other end of the resistor R4 is simultaneously connected to one end of the resistor R5, the negative input end of the operational amplifier A2 and the positive input end of the operational amplifier A3, the other end of the resistor R5 is simultaneously connected to one end of the resistor R6 and the output end of the operational amplifier A2, the other end of the resistor R6 is simultaneously connected to one end of the resistor R7, the negative input end of the operational amplifier A3 and the negative input end of the operational amplifier A4, the other end of the resistor R7 is simultaneously connected to one end of the resistor R8 and the output end of the operational amplifier A3, the other end of the resistor R8 is simultaneously connected to one end of the capacitor C1 and the positive input end of the operational amplifier A4, and the other end of the capacitor C1 is connected to the GND of the power supply;

[0014] The circuit of the equivalent capacitor Ceq2 is the same as that of the equivalent capacitor Ceq1.

[0015] Preferably, the resistance values ​​of the resistors R3 - R8 are selected based on the capacitance value of the equivalent capacitor Ceq1 being 10000 times the capacitance value of the capacitor C1 .

[0016] The beneficial effects of the present invention are as follows: the PI controller of the present invention converts voltage into current through a negative feedback circuit; the output voltage of the PI controller is obtained by injecting current into an RC branch composed of an equivalent capacitor and a resistor; and the value of the on-chip capacitor is amplified by using an impedance converter to obtain an equivalent capacitor, thereby achieving full integration of the PI controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a circuit diagram of a fully integrated analog PI controller in the present invention;

[0018] Figure 2is a circuit diagram of an equivalent capacitor in the present invention;

[0019] Figure 3 is a structural diagram of the gyroscope in the present invention;

[0020] Figure 4 This is a diagram showing the output results of the analog PI controller in the gyroscope of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0024] like Figure 1 As shown, the fully integrated analog PI controller of this embodiment includes an operational amplifier A1, MOS tubes M1-M3, a resistor R1, a resistor R2, a current source I1, and equivalent capacitors Ceq1 and Ceq2.

[0025] The positive input end of the operational amplifier A1 is the input end Vin of the analog PI controller, the negative input end of the operational amplifier A1 is connected to one end of the resistor R1 and the source end of the MOS tube M1 at the same time, and the output end of the operational amplifier A1 is connected to the gate end of the MOS tube M1; the drain end of the MOS tube M1 is connected to the drain end of the MOS tube M2, the gate end of the MOS tube M2 and the gate end of the MOS tube M1 at the same time; the drain end of the MOS tube M3 is connected to one end of the resistor R2, one end of the equivalent capacitor Ceq1 and the positive electrode of the current source I1 at the same time, and is the output end Vout of the analog PI controller; the other end of the resistor R2 is connected to the other end of the equivalent capacitor Ceq2, and the other end of the resistor R1, the other end of the equivalent capacitor Ceq1, the other end of the equivalent capacitor Ceq2 and the negative electrode of the current source I1 are connected to the GND of the power supply; the source ends of the MOS tubes M2 and M3 are connected to the VDD of the power supply.

[0026] The input voltage Vin is converted into current through the negative feedback resistor R1. The current is replicated through the MOS tube M2 and the MOS tube M3, and flows into the resistor R2 and the equivalent capacitor Ceq2 to generate the output voltage of the analog PI controller. The equivalent capacitor Ceq1 is a filter capacitor that filters out the high-frequency voltage component generated by the PI control. The current source I1 ensures that the input amplitude of the input voltage Vin will not be saturated after the system is closed. The input-to-output relationship of the analog PI controller is as follows:

[0027]

[0028] like Figure 2 As shown, the structure of the equivalent capacitor Ceq1 / Ceq2 of this embodiment includes an operational amplifier A2, an operational amplifier A3, an operational amplifier A4, resistors R3-R8 and a capacitor C1;

[0029] One end of the resistor R3 is one end of the equivalent capacitor Ceq1, one end of the resistor R3 is connected to the positive input end of the operational amplifier A2, the other end of the resistor R3 is simultaneously connected to one end of the resistor R4 and the output end of the operational amplifier A4, the other end of the resistor R4 is simultaneously connected to one end of the resistor R5, the negative input end of the operational amplifier A2 and the positive input end of the operational amplifier A3, the other end of the resistor R5 is simultaneously connected to one end of the resistor R6 and the output end of the operational amplifier A2, the other end of the resistor R6 is simultaneously connected to one end of the resistor R7, the negative input end of the operational amplifier A3 and the negative input end of the operational amplifier A4, the other end of the resistor R7 is simultaneously connected to one end of the resistor R8 and the output end of the operational amplifier A3, the other end of the resistor R8 is simultaneously connected to one end of the capacitor C1 and the positive input end of the operational amplifier A4, and the other end of the capacitor C1 is connected to the GND of the power supply.

[0030] By deriving the node voltage and current formula, the equivalent capacitance of the equivalent capacitance Ceq1 / Ceq2 structure is as follows:

[0031]

[0032] The analog PI controller of this embodiment is widely used in closed-loop systems, such as temperature control systems, pressure control systems, inertial measurement systems, etc. The following mainly uses the gyroscope in the inertial measurement system as a carrier to give a gyroscope system. The gyroscope system of this embodiment is as follows: Figure 3 As shown, it includes a driving loop and a detection loop;

[0033] The driving loop includes a driving shaft actuator 101, a driving end electrical model 102, a driving shaft transducer 103, a driving end transimpedance amplifier 104, a rectifier 105, the above-mentioned analog PI controller 106 and a variable gain multiplier 107;

[0034] The output end of the drive shaft actuator 101 is connected to the input end of the drive end electrical model 102, the output end of the drive end electrical model 102 is connected to the input end of the drive shaft transducer 103, the output end of the drive shaft transducer 103 is connected to the input end of the drive end transimpedance amplifier 104, the output end of the drive end transimpedance amplifier 104 is simultaneously connected to the input end of the rectifier 105, the input end of the variable gain multiplier 107 and the phase-sensitive demodulation clock signal input end of the detection loop, the output end of the rectifier 105 is connected to the input end of the analog PI controller 106, the output end of the analog PI controller 106 is connected to the input end of the variable gain multiplier 107, and the output end of the variable gain multiplier 107 is connected to the input end of the drive shaft actuator 101, forming a drive loop;

[0035] The detection loop includes a detection shaft actuator 108, a detection shaft electrical model 109, a detection shaft transducer 110, a detection end capacitance detection circuit 111, a phase-sensitive demodulation circuit 112 and a low-pass filter 113;

[0036] The output end of the detection axis actuator 108 is connected to the input end of the detection axis electrical model 109, the output end of the detection axis electrical model 109 is connected to the input end of the detection axis transducer 110, the input end of the detection axis transducer 110 is connected to the input end of the detection end capacitance detection circuit 111, the voltage output end of the detection end capacitance detection circuit 111 is connected to the voltage input end of the phase-sensitive demodulation circuit 112, the input end of the comparator 114 is the phase-sensitive demodulation clock signal input end of the detection loop, the output end of the comparator 114 is connected to the clock signal input end of the phase-sensitive demodulation circuit 112, the output end of the phase-sensitive demodulation circuit 112 is connected to the input end of the low-pass filter 113, and the output of the low-pass filter 113 is the output voltage V of the detection open loop. out , according to the output voltage V out Determine the input angular velocity of the gyroscope detection axis.

[0037] The driving loop is composed of 101-107, which is used to ensure that the resonator oscillates with equal amplitude on the driving shaft, wherein the analog PI controller 106 provides infinite loop gain for the low-frequency signal path after rectification to ensure the amplitude stability of the driving end; the detection loop is composed of 108-113, wherein the transducer output is an angular velocity signal modulated by the driving signal, and the signal is phase-sensitively demodulated and low-pass filtered to obtain an angular velocity output voltage signal, and the output signal reflects the input angular velocity. The clock of the phase-sensitive demodulation of the detection circuit is obtained by the output of the driving end transimpedance amplifier 104 through the comparator 114.

[0038] The capacitance magnification is set to 10000 times, and the values ​​of the capacitor C1 corresponding to the equivalent capacitor Ceq1 and the equivalent capacitor Ceq2 are set to 20pF and 2pF respectively. Then the capacitance value of the equivalent capacitor Ceq2 is 200nF, and the capacitance value of the equivalent capacitor Ceq1 is 20nF. Put this parameter PI controller into the gyroscope system, and the result is shown in the figure. Figure 4 .

[0039] Figure 4 In the figure, VPI is the output of the analog PI controller 106, and VTIA is the output of the transimpedance amplifier 104. In the self-excited oscillation stage of the gyroscope, 101-104 and 107 form a positive feedback loop. At this time, the output of the analog PI controller 106 is the maximum value. The analog PI controller controls the variable gain multiplier 107 to work at the maximum gain, and makes the loop meet the Barkhausen positive feedback criterion. Under the excitation of the circuit noise, the loop makes the resonator displacement (the output of the driving end electrical model 102) increase continuously. When the resonator displacement oscillates to the reference amplitude, the analog PI controller starts to work and gradually controls the resonator displacement to the reference amplitude. This process is shown in FIG. Figure 4 In the middle amplitude control stage, under the action of the analog PI controller, the amplitude of the resonator is stably controlled. Figure 4 Medium amplitude stable stage.

[0040] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. Fully integrated analog PI controller, characterized by: It includes an operational amplifier A1, a MOS tube M1, a MOS tube M2, a MOS tube M3, a resistor R1, a resistor R2, a current source I1, an equivalent capacitor Ceq1 and an equivalent capacitor Ceq2; The positive input terminal of the operational amplifier A1 is the input terminal Vin of the analog PI controller, the negative input terminal of the operational amplifier A1 is connected to one end of the resistor R1 and the source terminal of the MOS tube M1 at the same time, and the output terminal of the operational amplifier A1 is connected to the gate terminal of the MOS tube M1; The drain end of the MOS tube M1 is simultaneously connected to the drain end of the MOS tube M2, the gate end of the MOS tube M2 and the gate end of the MOS tube M1; The drain end of the MOS tube M3 is simultaneously connected to one end of the resistor R2, one end of the equivalent capacitor Ceq1 and the positive electrode of the current source I1, and is the output end Vout of the analog PI controller; The other end of the resistor R2 is connected to the other end of the equivalent capacitor Ceq2, and the other end of the resistor R1, the other end of the equivalent capacitor Ceq1, the other end of the equivalent capacitor Ceq2 and the negative electrode of the current source I1 are connected to the GND of the power supply; The source ends of the MOS tube M2 and the MOS tube M3 are connected to the power source VDD.

2. The fully integrated analog PI controller according to claim 1, characterized in that The equivalent capacitor Ceq1 includes an operational amplifier A2, an operational amplifier A3, an operational amplifier A4, resistors R3-R8 and a capacitor C1; One end of the resistor R3 is one end of the equivalent capacitor Ceq1, one end of the resistor R3 is connected to the positive input end of the operational amplifier A2, the other end of the resistor R3 is simultaneously connected to one end of the resistor R4 and the output end of the operational amplifier A4, the other end of the resistor R4 is simultaneously connected to one end of the resistor R5, the negative input end of the operational amplifier A2 and the positive input end of the operational amplifier A3, the other end of the resistor R5 is simultaneously connected to one end of the resistor R6 and the output end of the operational amplifier A2, the other end of the resistor R6 is simultaneously connected to one end of the resistor R7, the negative input end of the operational amplifier A3 and the negative input end of the operational amplifier A4, the other end of the resistor R7 is simultaneously connected to one end of the resistor R8 and the output end of the operational amplifier A3, the other end of the resistor R8 is simultaneously connected to one end of the capacitor C1 and the positive input end of the operational amplifier A4, and the other end of the capacitor C1 is connected to the GND of the power supply; The circuit of the equivalent capacitor Ceq2 is the same as that of the equivalent capacitor Ceq1.

3. The fully integrated analog PI controller according to claim 1, characterized in that The resistance values ​​of the resistors R3 - R8 are selected based on the fact that the capacitance value of the equivalent capacitor Ceq1 is 10000 times the capacitance value of the capacitor C1 .

4. A gyroscope system, characterized in that: Including driving loop and detection loop; The drive loop comprises a drive shaft actuator (101), a drive end electrical model (102), a drive shaft transducer (103), a drive end transimpedance amplifier (104), a rectifier (105), an analog PI controller (106) and a variable gain multiplier (107); the analog PI controller (106) is implemented by using any one of the fully integrated analog PI controllers described in claims 1 to 3; The output end of the drive shaft actuator (101) is connected to the input end of the drive end electrical model (102), the output end of the drive end electrical model (102) is connected to the input end of the drive shaft transducer (103), the output end of the drive shaft transducer (103) is connected to the input end of the drive end transimpedance amplifier (104), the output end of the drive end transimpedance amplifier (104) is simultaneously connected to the input end of the rectifier (105), the input end of the variable gain multiplier (107) and the phase-sensitive demodulation clock signal input end of the detection loop, the output end of the rectifier (105) is connected to the input end of the analog PI controller (106), the output end of the analog PI controller (106) is connected to the input end of the variable gain multiplier (107), and the output end of the variable gain multiplier (107) is connected to the input end of the drive shaft actuator (101); The detection loop is used to obtain the input angular velocity of the gyroscope detection axis under the control of the phase-sensitive demodulation clock signal.

5. The gyroscopic system according to claim 4, characterized in that: The detection loop includes a detection axis actuator (108), a detection axis electrical model (109), a detection axis transducer (110), a detection end capacitance detection circuit (111), a phase-sensitive demodulation circuit (112), a low-pass filter (113) and a comparator (114); The output end of the detection shaft actuator (108) is connected to the input end of the detection shaft electrical model (109), the output end of the detection shaft electrical model (109) is connected to the input end of the detection shaft transducer (110), the input end of the detection shaft transducer (110) is connected to the input end of the detection end capacitance detection circuit (111), the voltage output end of the detection end capacitance detection circuit (111) is connected to the voltage input end of the phase-sensitive demodulation circuit (112), the input end of the comparator (114) is the phase-sensitive demodulation clock signal input end of the detection loop, the output end of the comparator (114) is connected to the clock signal input end of the phase-sensitive demodulation circuit (112), the output end of the phase-sensitive demodulation circuit (112) is connected to the input end of the low-pass filter (113), and the output of the low-pass filter (113) is the output voltage V of the detection open loop. out , according to the output voltage V out Determine the input angular velocity of the gyroscope detection axis.

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